Activation of multiple defects in zinc aluminate through gamma and UV irradiation

Versatile luminescence has always been the source of inspiration to explore the complex trap distribution in semiconducting oxides. In the continuation of reported investigation of effect of fuel type on the trap distribution and other properties of zinc aluminate (Jain et al., Sci. Rep. 10 (2020) 385), effect of fuel blends on defect structure is examined. A gradual transition from narrow to broad glow curves is observed on substituting urea fuel by monoethanolamine (MEA) during synthesis. In addition, type of irradiation (γ and UV radiation) is having a different impact on populating the traps and hence recombination kinetics. Deeper traps started contributing more with the increase in MEA fuel. Deconvolution of complex curves has enabled to visualize the presence of multiple traps with overlapping wavefunctions. Zn/Al vacancies act as hole trap centres and AlZn• antisite defect as an electron trap aided by neutral and charged oxygen vacancies (F and F+ centres) situated somewhat deeper in the forbidden gap. In order to provide a lucid understanding, phenomenon of trapping, de-trapping, re-trapping and recombination is depicted through a band model diagram. Presented study can be useful in tuning various properties of ZnAl2O4. •Fuel blend combustion approach is utilized to synthesize ZnAl2O4 nanoparticles.•Gamma and UV irradiation activated multiple defects in ZnAl2O4 nanoparticles.•Zn/Al vacancies, AlZn• antisite defects, neutral and charged oxygen vacancies serve as traps.•Observed defects can contribute significantly in tuning the various properties of ZnAl2O4.